Most compact fluorescent lamp ballasts draw current from the power line only during a relatively short time period near the peak of the input AC voltage waveform. Disadvantageously, this creates a highly distorted input current waveform that, in turn, causes the input power factor to be low, typically about 0.5 to 0.6. Another area for improvement in compact fluorescent lamps is dimming operation, specifically, dimming the lamp to low light levels, while maintaining steady, non-flickering operation.
Accordingly, it is desirable to provide a high power factor ballast for a discharge lamp, particularly a compact fluorescent lamp.
Further, it is desirable to provide a high power factor ballast having dimming capability.
Still further, it is desirable to provide a high power factor ballast having the capability to dim the discharge lamps to relatively low levels, while maintaining steady, non-flickering operation.